Fiber-mixing and fabricating apparatus



6. S. FRANCIS, JR

FIBER-MIXING AND FABRICATING APPARATUS Sept. 20, 1960 INVEN TOR.

AT T 0RNEY Original Filed April 14, 1944 United States PatentFIBER-MIXING AND FABRICATING APPARATUS Carleton S. Francis, In, WestHarwich, Mass., assignor to American Viscose Corporation, Philadelphia,Pa.,

a corporation of Delaware 6 Claims. (Cl. 154-29) This invention relatesto textiles and the like, and more particularly to such productscomprising mixtures of potentially adhesive fibers and non-adhesivefibers, and to an improved process for producing the same.

This application is a continuation of my prior application Serial No.530,953, filed April 14, 1944, now abandoned. That prior applicationdiscloses a method of producing textile felts and the like in accordancewith which non-adhesive fibers are associated with potentially adhesivefibers concurrently with formation of the latter.

Prior art processes for the production of textile felts and the like,such as webs, mats, batts, etc., have involved carding and/or combingoperations which necessitated in every instance the use of comparativelylong fibers, since the shorter fibers cannot be carded and/or combedsatisfactorily. In such webs coming from the carding machine,substantially all of the relatively long fibers are parallelized in thedirection of the longitudinal dimension of the web, and the web isinherently structurally weak and relatively easily torn apart orshredded when subjected to tension applied laterally or transverselythereto, because only a few if any, of the fibers extend across thewidth or thickness of the web, and hence the web is not nearly asresistant against stress or strain applied in those directions as it isagainst stress or strain directed longitudinally of the web.

The fibers in such carded webs or mats tend to occur in the form ofsuperimposed layers, and when cut through, i.

cut transversely, a large proportion of laminated sections w and suchwebs tend to separate when subjected to even light tension. Furthermore,satisfactory felted fibrous mats or webs of extremely low density andgreat thickness cannot be obtained by the prior art processes. Thickwebs obtained by superimposing a multiplicity of thinner carded and/ orcombed webs upon one another show only moderately fair tensile strengthand tend to peel off in individual layers in use.

It is a general object of the present invention to provide a new processfor making felts, comprising admixtures of pre-formed potentiallyadhesive fibers and preformed non-adhesive fibers. The expressionpre-formed potentially adhesive fibers is meant to refer to fibers whichare capable of being rendered tacky or adhesive, either superficially ormore completely through the individual fiber body, as desired, but whichare not in tacky or adhesive condition at the time of mixing; and theexpression pre-formed non-adhesive fibers is meant to refer to fiberswhich, although they may be capable of being rendered tacky or adhesiveunder some conditions, are not capable of being rendered tacky oradhesive under the conditions obtaining in the process of the presentinvention.

A further object of the invention is to provide a new process for theproduction of felted fibrous articles which 2,953,187 Patented Sept. 20,1960 insures uniform mixing of the two types of fibers withoutagglomeration and according to which products of even thicknessthroughout are obtained and which results in uniform distribution of thecommingled fibers from surface to surface of the product.

Another object is to provide a process according to which it is possibleto utilize organic fibers of extremely short length, such as normallyare considered non-feltable, that is, fibers which cannot be felted byconventional methods. Still another object of the invention is toprovide a process for producing fibrous felted products which does notrequire a carding and/ or combing operation.

A further object of the invention is to produce felted products in whichthe fibers extend haphazardly in all directions and in which there areno cleavage planes regardless of thickness.

These and other objects are attained by the present invention, accordingto which, generally speaking, the preformed potentially adhesive fibersand the non-adhesive fibers are blown together, and thus intimatelycommingled and admixed, and the mixtures are treated to activate thepotentially adhesive fibers to bind fibers in the product. While thepotentially adhesive fibers are in the activated state, the product maybe subjected to a compacting step, if desired.

In accordance with one embodiment of the invention, the two types offibers are impelled by blowing them with air or any other gaseous orvaporous, but preferably gaseous medium into a common mixing anddepositing cham bet, or successively into a mixing chamber and then intoa depositing chamber. The pre-formed fibers in suspension in theaeriform current are thus agitated and whirled about in a confinedspace, so that they freely mix and intermingle without agglomeration,after which they are permitted to settle out on a collecting surface.The thus uniformly mixed fibers fall on one another in a haphazardmanner to form a fibrous matted web or batt in which the fibers projectin all directions within and throughout the product. The web thusobtained has the appearance of a criss-crossed network of fibers, all ofwhich are interlaced together, in unarranged haphazard distribution, andin which there is relatively little if any distribution of the fibers inexact parallelism or in side-by-side relation. The web is an integratedfibrous structure in which distinct layers of fibers are not detectable,and which in transverse cross-section is practically devoid of laminatedsections.

The product is adapted to be treated to activate the potentiallyadhesive fibers, without damage to the nonadhesive fibers, to bindfibers in the product to form a reticulated webbed structure extendingthroughout the product. When so treated, the fibers are anchored attheir points of contact wherever the potentially adhesive fibers occurthroughout the structure, and are firmly set in the non-parallelizedcondition, the felted product finally obtained having excellentresistance against both compressive, tensile, and shearing stress orstrain applied either longitudinally, laterally, or transverselythereof.

The web or mat thus obtained is adapted to be used as such, or it may beshaped into any desired form. Alternatively, the potentially adhesiveand non-adhesive fibers may be blown directly onto any desired form,such as a form for producing hat shapes, and then activated andcompacted by heat and pressure, and deactivated.

Among the non-adhesive fibers' which may be employed are those whichalthough they may be rendered adhesive by some treatment, are notrendered adhesive under the conditions used to activate the potentiallyadhesive fibers associated therewith, and including natural fibers, suchas wood pulp fibers, cotton, linen, jute, kapok, wool, hair, and silk;and synthetic fibers such as cellulose 3 fibers of the type of cellulosehydrate, cellulose derivatives such as cellulose esters, mixed celluloseesters, cellulose ethers, mixed cellulose ester-ethers, mixed celluloseethers, cellulose hydroxy-ethers, cellulose carboxy-ethers, celluloseether xanthates, cellulose xantho-fatty acids, cellulose thiourethanes;natural and synthetic rubber and derivatives thereof; fibers made ofalginic acid, gelatine,

casein; and mineral fibers such, for example, as spun 'glass, asbestos,mineral wool, and the like; and fibers made of natural and syntheticresins which should be of v such type that they are not rendered tacky"when the potenti-ally adhesive fibers are rendered tacky; also fibersand filaments made by slitting, cutting, or shredding nonfibrous filmssuch as cellophz'me.

The potentially adhesive fibers may be composed of a wide variety ofmaterials and may comprise any material capable of being formed intofibers which have an inherent tackiness under conditions such that thenomadhesive fibers are not damaged or rendered tacky, and which are nottacky at room temperature. Examples of' the potentially adhesive fibersare thermoplastic fibers, such as those of cellulose acetate or othercellulose esters and ethers, or mixed cellulose esters such as cellulosea'cetate-propionate, or cellulose acetate-butyr-ate, in plas- V ticizedcondition; also resins'as, for example, cheap natural resins such asshellac, dammar, copal and the like, "and synthetic resins eitherpermanently thermoplastic or .thermosetting, but in the thermoplasticstate formed by the polymerization or condensation of various organiccompounds such as coumarone, indene or related hydrocarbons, .vinylcompounds, styrene, sterols, aldehydes, furfural, ketones, urea,thiourea, phenol-aldehyde resins such as copolymers of vinyl halide andvinyl acetate, co-

polymers of vinyl halide and an acrylic acid derivative,

copolymers of vinyl compound and styrol compound;

and also a mixture of resins, such as a mixture of vinyl resins andacrylic acid resins or methacrylic acid resins, a mixture of polyolefineresins and phenol-aldehyde resins, or a mixture of two or more resinsfrom the different classes just named. There may be employed also fibersmade from rubber latex, crepe rubber, gutta percha, balata, and thelike. Further, the potentially adhesive fibers may be mixtures of thecellulose derivatives with resin or rubber, such as, for example, amixture of cellulose nitrate and an acrylic acid resin, a mixture of aremixed together by blowing in accordance with the present invention areproduced may contain added agents for obtaining special eifects. Forexample, the parent fiber-forming material for the'potentially adhesivefibers may contain hardeningagents' in the case of resins, for instance;while the fibenforming material for either the potentially adhesive orthe non-adhesive fibers may contain latent activating agents, dyes,pigments, mothproofin'g agents, firepro'ofing agent's, waterproofingagents, and

either unmodified or modified with oils, urea-aldehyde the like. 7

The fibers may be pre-formed in any suitable manner.

Thus, either type of fiber may be obtained by cutting previously formedcontinuous filaments to the desired length, or, in the case of thepotentially adhesive fibers, they may be pre-formed by dispersing thefiber-forming material while in liowable conditiom'that is, in solution,plastic, or molten condition, under sufiicient pressure to form amultiplicity of fibers, into a setting fluid, e.g., a liquid or agaseous atmosphere, as taught in my copending application: Serial No.381,292, filed March 1, 1941, now Patent 2,357,392. .Such pre-form'ationof the potentially adhesive fibers-is carried out in a chamber which ,isseparate from but may be connected with the chamber into which thepotentially adhesive and non-adhesive fibers are blown andtheintermingled fibers allowed to deposit in t heform of a mixed fibrousproduct. p In order to efiect a bindingtoget'her of the mixedunagglomerated intermingled fibers, thepotentially adhesive fibers areactivated wherever they occur throughout the entire structure, or atselected .points therein, by the application of a bonding agentfsuch asheat or solvent, to cause at least a partial adhesion between thefibers. Among the methods which may be used for activation, are thefollowing, which methods may be practiced singly .or in combination.

(a) When the potentially adhesive fibers are thermoialastic, they may beactivated by heat applied with or without pressure, and a preferredmethod of activation is to blow dry hot air through the product. .Intreating webs of appreciable thickness, the air may be blown first inone direction and then in the opposite direction through the web toavoid non-uniform activation and dislocation of the fibers in the -web.

(b) The potentially adhesive fibers may be activated by applying to thefibrous mixture a solvent or swelling agent or mixtures thereof'withdiluents, under such conditionsof mementos-21nd temperature as to renderthe potentially adhesive fibers tacky. For-example, fibers of .benzoylcellulose and a vinyl resin, or a mixture of ethyl I cellulose andshellac.

A preferred class of vinyl resin from'which the fibers may be formed arethe copolymers of vinyl chloride with vinyl acetate or vinyl cyanide,and after-chlorinated copolymers of vinyl chloride and vinyl acetate.

The resins above mentioned may be classified as:

(a) Heat non-convertible resins such for example 'as glycol polybasicacid resins, vinyl resins (Particularly those of the preferred classabove) and the acid type phenolaldehyde resins, and the like.

(b) Heat convertible or thermosetting' resins such for example asglycerol-polybasic acid resins, polyolefin resins,- phenol-aldehyderesins and the like.

(0) An element-convertible resins (which becomes'infusible through theaction of certain elements; suoh as oxygen and sulfur) such for exampleas glycerol-poly basic acid -drying oils, resins, and olefine-sulfurresins.

The fiber-forming material from which the fiber-s which organiccellulose derivativessuc'zhas cellulose esters may 50 :be renderedadhesive by solvents such as acetone, ethyl acetate, butyl 'acetate,'andthe like; i k (c) latent activating agent may be combined withthe.;potentially adhesive fibers and/ or with the nonadhesive fibers.Such agent may be rendered activeby a subsequent treatment, such as bytreatment with chemical agents,'heat or irradiationfthus producing asimultaneous activation of the potentially adhesive fibers in selectedareas. For example, fibers may be impregnated with a liquid which, atroom temperature is a non-solvent therefor, but which at a higheror-'lower temperature 'is capable of activating the potentially adhesivefibers.

7 Also, when the mats, webs, or-the like comprise thermoplastic fibers,they may beactivated by subjecting them to-steam, with or withoutpressure, especially where it is desired to produce a felted web'or "thelike characterized by extreme softness, low density, and relativelygreat thickness It'is also possible to'activate the activatable fiberspresent-in the fibrous web or mat'by subjecting the same to a highfrequency electric current.

A "plasticizer may be applied to the :fibers and/ or to the productbefore activation. The plasticizer may function to increasethefiexibility of'the fibers, 'and, when employed with thermoplasticfibers, the plasticizer may serve, in addition; to :lower the thermalsoftening point. T The plasticized' thermoplastic fiberscan be renderedadhesive by heating to a temperature below that at which thenon-thermoplastic textile fibers associated therewith would bedetrimentally affected by such heating. The plasticizer may be allowedto remain in the product, or it may be removed by suitable treatment,such as washing and extraction, thus again elevating the thermalsoftening point of the thermoplastic material and preventingreactivation upon ironing.

During or after activation, .the products'may be compacted, if it isdesired to'produce a web of increased density, and the compacting may beeffected in any suitable manner, as by pressing, squeezing, andtensioning. For example, the mechanically applied pressure exerted onthe activated material during and/ or after activation, and/or duringcalendering, embossing, printing, or dyeing will effect compacting ofthe fibers. Also the fibrous mat or web, in activated condition, may bepassed between pressure rolls to compress the mixed fibers, or it may besubjected to tension in one or both directions.

After activation and compacting, if the latter is employed, the fibrousproduct is treated to deactivate the adhesive fibers, that is, to renderthe adhesive fibers nontacky, so as to fix the new relationship of themixed fibers. The nature and extent of the deactivation treatmentdepends, inter alia, upon the nature and extent of the activatingtreatment and upon the proportion and kind of potentially adhesivefibers used. If activation has been accomplished by heat, deactivationmay be accomplished by heating for a prolonged period, or to a highertemperature in the case of thermosetting resins or by cooling; and ifactivation is by means of a solvent, deactivation may involve extractionof the solvent as by washing, evaporation or decomposition. The removalof the activating agent depends upon whether its presence in the productis desirable or objectionable.

The activation, compacting, and deactivating treatments may be carriedout independently of or simultaneously with various treatments common tothe fabrication and finishing of felts, or the laminating and sealing ofsheet materials when the products are applied to the latter purposes.

The properties of the finished product depend upon various factors,including the nature and proportion of the potentially adhesive fiberspresent in the product, the extent to which such fibers have beenactivated, whether or not the product is compacted by pressure or thelike, and if so compacted the relative adhesiveness of the fibers duringcompacting, as well as the nature of the deactivation treatment, and allsuch factors may be pre-selected and controlled for the production ofproducts of any degree of pliability, firmness, density or porosity, asmay be desired.

The relative proportions of potentially adhesive and non-adhesive fibersused depends upon the final product desired, and may vary Within quitewide limits, but where either or both types of fibers are much shorterthan average length, it may be desirable to utilize a comparativelylarge proportion of the potentially adhesive fibers, in order to insurea firm binding together of the short fibers in the product.

The extent of activation may be varied considerably. Thus thepotentially adhesive fibers may be rendered adhesive while maintainingtheir fibrous form, and may be present in such quantity that theresulting product, with or without compacting thereof, is characterizedby a high degree of porosity, and is useful for many purposes, includingbattery separators, filtering media, or as insulating material or thelike. On the other hand, the potentially adhesive fibers may be renderedsufficiently fluid to spread under pressure to form a film in which thenon-adhesive fibers are firmly embedded, thus yielding an impermeableproduct which may be used in fabricating waterproof articles such asraincoats, for example.

The process of the invention is adapted for the pro- .duction of varioustypes of fiat felts, per se, such as webs,

mats, batts, etc., of any desired degree of thickness which may beobtained by a single deposition of the fibers commingled by blowing, andwhich products may be used as such, or subsequently shaped into anydesired form. Thus, there may be obtained shaped gaskets for liquidseals in mechanical equipment, shaped oil and gas filters, shapedwashers, etc. There may also be obtained shaped products in whichabrasive particles are included in the fibers or embedded in the surfacethereof, such as abrading devices suitable for abrasive purposes, as forgrinding, polishing, buifing or like operations, and including grindingand polishing wheels, flexible abrasive discs, sanding and polishingbelts, blocks, pads, and other shapes. The abrasive materials mayinclude any of the abrasive particles commonly in use, such as siliconcarbide, diamonds, boron carbide, fused aluminum oxide, flint, corundum,emery, rouge, and similar substances. The size of the abrasive particlesmay vary from the finest polishing or bufiing powders to the coarsergrit sizes used in grinding.

The fibers commingled by blowing in accordance with this invention, mayalso be collected directly on any suitable form, such as the forms usedin the manufacture of hats, for example, and then compacted by heat andpressure, and deactivated. Thus, it is possible to produce directly suchfelted bodies as hats or the like, and since the activation andcompaction of the mixed fibers is efiected after deposition thereof onthe form, the shape of the desired article ispermanently preserved.

The process is also advantageous for the production of high qualitypapers, since when fibers of paper-making length are blown together andthen permitted to deposit, the papers obtained are softer and fiuflierthan those which can be obtained by conventional water-laying methods.

In the case of flat felts, such as batts or webs, if the product firstobtained is capable of further activation under appropriate conditions,it may be used in the production of laminated products. In thelaminating art, the web containing the potentially adhesive fibersbefore or after such further activation and preferably the former, maybe disposed between a layer of a textile fabric, felt, paper, wood,film, glass or the like, and a layer of the same or of differentmaterial, and the composite product may be subjected to sufficientsolvent or heat and pressure to activate the potentially adhesive fibersand unit the layers to each other. In the sealing art, the webcontaining potentially adhesive fibers may be inserted between theoverlapping or contiguous surfaces of a wrapper or carton, or betweenthe folds or overlapping area of a fabric, and the same closed andsealed by the application of heat and pressure, or by the application ofpressure and a solvent for the fibers with or without the use of heat.Instead of placing the web between two layers, as above described, theweb may be superimposed on the surface of any material which it isdesired to coat. The product is then treated to activate the potentiallyadhesive fibers to cause the web to adhere to the material with which itis in contact. In this instance, it may be desirable to activate the webto a sufficient extent to cause the potentially adhesive fibers to flowto form a continuous film. While the fibers are still adhesive, pressuremay be applied to insure the production of a smooth, glossy surface.

The products of the invention may at any time be em- .bossed,calendered, molded, or otherwise shaped, in whole or in part, to deformthe surface while the potentially adhesive fibers are still tacky or ina softened state, and then subsequently treated to deactivate the fibersto set the product in the desired form or surface condition to produceeffects such as grain, luster, smoothness or designs, by suitable means,used hot or cold, and with or without the aid of agents which soften,swell, or plasticize the material acted on.

Further, the fibrous products produced according to the invention may becolored before, during or after activation, compaction and/ordeactivation, by dyeing, printing, for example with inks containingpigments or dye;

are drawn downwardly-through chamber 4 onto succesthe, rolls and becomescool.

fromthe card by the'doffer roll 18. The tube 17 is constuffs which areresistant to the activating, compacting, and deactivating treatments. Ifdesired, where the activating and deactivating agents are solvents, theymay be added to the dyebath or the printing ink.

In the accompanying drawing illustrative of the invention Figure 1 is aside elevation of one embodiment of suitable means for blowingpre-formed fibers together in accordance with my inventio'n, V

Figure 2 is a side elevation of another embodiment'of means for carryingout the invention, and

Figure 3 is a side elevation of still another embodiment of suitablemeans for Carrying out the invention,

When using the apparatus shown in Figure '1, a-compositio'n suitable forforming potentially adhesive fibers is dispersed by means of the spraygun 1 into a gaseous atmosphere contained in chamber 2; Anymaterialwhich is not formed into fibers is caught on shelf 3 and may beremoved at intervals. Solvent is removed from chamber 2 through ascreened vent 3a, by means of a suction device (not shown). Thepotentially adhesive fibers thus formed are withdrawn from chamber 2 andblown into chamber 4 through conduit 5 by blower 6. Simultaneously amultiplicity of non-adhesive fibers are blown into chamber 4, preferablyin a direction opposite to that of the other fibers through conduit 7 byblower 8. The fibers are scattered about in the chamber by theturbulence of the air streams, and are thoroughly mixed together beforesettling out. The two types of fibers are thus brought together at apoint sufiiciently removed from the'point of deposition to permitgoodcommingling during deposition. The mixed fibers then come to rest onthe surface of an'endless belt 9 made of flexible material such astextile, metal, leather or the like, which belt is preferably positionedin a horizontal plane at the base 'of chamber 4, and serves as acollecting surface. Preferably, belt 9 is provided with a multiplicityofsmall uni- "formly distributed perforations and runs over a similarlyuniformly perforated false botto'm or-screen 10'. A suction pump :11, isconnected to the region below the belt in'chamber 4, to create a downdraft through endless belt '9 as it passes through the chamber. As thefibers are deposited on one portion of the belt, the suction at otherpoints thereof is increased so that the intermingled fibers siveportions of belt 9, which assists in a uniform distribution of thefibers over the belt surface, and results-in the production of a web orbatt of uniform thickness throughout. The mat 12 is carried on the beltfi'o'm the chamber and through pinch rolls '13 and 14, which compress orcompact the mat and enable it to be removedv from the belt foractivating or finishing operations. If

I the potentially adhesive fibers are thermoplastic, the rolls 13 and 14may be heated sufiiciently to activate the. thermoplastic fibers to anydesired extent, the activated fibers being deactivated when the mat 12passes from Air may be permitted to escape from chamber 4 through ascreened exhaust pipe 15, if the suction pump isnot used. Whenpotentially adhesive fibers which are activatable by means of an organicsolvent are used, the solvent may be sprayed on the fiber batt 12 as itis carried on the belt, as at point A, so that the fibers are in anadhesive condition'when passing through the pressure rolls '13 and 14.In the manufacture of paper tissues, the belt 9 may be considered ascomprising the Wire screen of the paper-making machine.

Referring n'ow'more particularly to'Figure '2, one type of the jfibersmay bepassed'over the card 16, and a suction tube 17 may be arranged toreceive the fleece taken nected to a hopper 19, feeding directly to thesuction-side of a: blower 20. The hopper is closed otherwise, except'for a duct 21 by which the other type of fibers *may be introduced. Thefibers may be introduced into duct 21'by any suitablemeans, such as byanothercard anddo'fier system. Alternatively the duct21 may be omittedand the two types of fibers, after mixing may be passed over the card 16and-sucked therefrom.

Blower 20 discharges upwardly into" an inverted U- shaped duct. Thefibers are'blown upwardly through one leg 22 of the duct, and then falldownwardly through leg 23 thereof onto aperforate form 24. A suctionpump 25 is positioned under leg 22 to assist in drawing the commingledfibers onto'the form 24. The'fibrous shape or form thus obtained maythen be activated and compacted by heat and pressure and the activatedfibers deactivated.

in Figure 3 there is shown a chamber 4a, into which potentially adhesivefibers are blown through conduit 26 by blower 27, and into whichnon-adhesive fibers are blown by blower 28 through conduit 29. Thefibers settle out and come to rest on the surface of endless belt 30,which is preferably of the same type and arranged on a false bottom overa suction pump, in the same manner as described in connection withFigure l. The mat 31 is carried on the belt from chamber 4a. Positionedalong the path of travel of the web or mat on belt 30 is an end lessscreen belt 30a.- The web and belts pass between rollers 32 and 33 andthrough a heating zone. As it passes'through such zone, air drawn intoheating cabinet 34 through inlet 35 is directed to the web "by means ofconduit 36 through the action of blower 37. The heated air is drawndownwardly through the mat by means of the exhaust pump 38 anddischarged to the atmosphere. Mat 31 in activated condition passesfrom'the heating zone between rollers '39 and 40 and directly into aconfined cooling or deactivating zone, at which point cool air isdirected on the web by blower 41 through conduit 42, and drawndownwardly therethrough by means of exhaust blower 43. Web 31, which maybe very thick (as much as eight inches or more) after it leaves chamber4a undergoes a certain amount of compacting, and hence decreases inthickness, as it passes through'the heating zone, and the rollers '39and 40 maybe suitably adjusted to take into account such changes in theweb due to the force of the air current thereon and the confrontingreaches of the belts between rolls 32, 33 and 39, 40 are converging, asshown. Rolls 39 and 40 may be spaced apart, so that they serve merely toassure confinement and contact of the 'web 31 between the belts in theheating zone without exerting substantial pressure thereon. Or they maybe adjusted to applya substantial compacting pressure to reduce the webto any thickness and density desired. Rolls 44 and 45 are preferablyspaced apart the same distance as rolls 39 and 40, so that these 'twopairs of rolls co-operate to maintain the proper thickness of the web 31during cooling. Additional pairs of rolls may be interposed between thepairs 39, 40 and 44, 45, so that the belts '30 and 30a have confrontingor'opposed parallel reaches and to assure that the desired thickness ofthe web, mat or batt is produced.

Fibers of any suitable length may be admixed to form a felted product inaccordance with the invention, and the fibers may' be blown togetherwithout resort to carding and/ or combing operations; or if preferredfor any reason, the fibers may be pre-carded or combed either inadmixture 'or individually and then blown together. Fibers of spinnablelength, or of carding or paper-making leng-thrnay be blown together, andthe potentially adhesive fibers may be of the same length as, or of adifferent length from the non-adhesive fibers. However, the invention isparticularly useful where it is desired to combine and mix fibers theaverage length of which is less than normal feltable length, that is,fibers which are so short that they cannot be successfully combined andfelted by prior art conventional methods. Thus it becomes pos- "sible,because of my invention, to used fibrous material which previouslyhasbeen considered as waste and discarded, such waste including shearflock, that is,the fuzz removed from fabrics and felts during shearingoperations-cotton linters, so-called ileather dust, that is, shortleather fibers, the short fiuify waste thrown out of carding and/orcombing machines, the waste fiom reeling, war-ping, winding, weaving andcop bottoms, the waste from slubbing, roving, and wool tops, and in factall short fibers or fibrils which ordinarily do not find use in themanufacture of commercial products.

It is particularly advantageous to blow the two types of fibers into achamber or the like separately but simultaneously, and preferably at apoint considerably removed from the depositing surface and from opposingpoints outside the chamber, as specifically illustrated, since theconfluence of the air streams creates eddies and crosscurrents whichfacilitate mixing of the fibers in suspension.

By way of illustration but not of limitation, there are given thefollowing examples of products produced in accordance with theinvention.

Example I Viscose rayon staple and fibers consisting of a copolymer ofvinyl acetate and vinyl chloride, which were from about two inches totwo and one-half inches long, were blown together and allowed to settle.The web thus obtained, which comprised 20% rayon staple and 80%copolymer, was activated, compacted and deactivated, using the apparatusshown in Figure 3. A compressed web was obtained in which the rayonfibers were firmly bonded together by the resin fibers, and when cuttransversely, the web was found to be substantially free of laminatedsections, and was characterized by excellent resistance to tearing undertension applied laterally, transversely or longitudinally.

Example II Cotton linters (40%) and fibers consisting of a copolymer ofvinyl acetate and vinyl chloride (60%) and which were 5 long, were blowntogether and permitted to settle out in the form of a matted web. Theweb was activated by blowing hot air therethrough in one direction,after which the web was deactivated by cooling. The product was a softporous mass.

Example 111 Cellulose acetate fibers about one-half inch long (30%) andviscose rayon staple (70%) were blown together and then permitted tosettle out. The web thus formed was heated to activate the celluloseacetate fibers, compacted and deactivated. The conditions were such thata compar-atively stiff fibrous web was finally obtained.

Since changes may be made in practicing the above invention withoutdeparting from the spirit and scope thereof, it is to be understood thatthe foregoing description and specific illustrations are illustrativeonly, and the invention is not to be limited except as defined by theappended claims.

I claim:

1. A machine for making felt-like fibrous webs, mats, bats, or the likecomprising a pair of air-pervious belts having confronting parallelreaches preceded by confronting converging reaches, means for moving thebelts through the confronting reaches in the same direction, a chamberhaving a discharge opening immediately adjacent the entrance to theconfronting converging reaches of the belts, means for delivering fibersthrough the chamber and its discharge opening into the space between theconfronting reaches of the belts, and means for blowing a heated gaseousmedium through the confronting reaches of the belts and the fibrousmaterial therebetween, said fiber delivering means comprising blowershaving their discharge ducts connected to opposite walls of the chamber,and separate means for supplying fibers to the suction ducts of theblowers.

2. A machine for making felt-like fibrous webs, mats, batts or the likecomprising a pair of air-pervious belts having confronting reachesmoving in the same direction,

a plurality of pairs of rolls spaced apart in the direction of movementof the confronting reaches, the confronting reach of one of the beltspassing over one roll of each pair, the confronting reach of the otherbelt passing over the other roll of each pair, the spacing between theindividual rolls of at least two pairs other than the pair adjacent theentrance of the belts to their confronting reaches being substantiallythe same and being less than the spacing between the rolls of the pairadjacent said entrance to thereby provide a converging portion followedby a parallel-spaced portion between the confronting belt reaches, achamber having a discharge opening immediate 1y adjacent the entrance tothe confronting converging reaches of the belts, means for deliveringfibers through the chamber and its discharge opening into the spacebetween the confronting reaches of the belts, and means for blowing aheated gaseous medium through the confronting reaches of the belts andthe fibrous material therebetween, said fiber delivering meanscomprising blowers having their discharge ducts connected to oppositewalls of the chamber, and separate means for supplying fibers to thesuction ducts of the blowers.

3. A machine for making felt-like fibrous webs, mats, batts, or the likecomprising a pair of air-pervious belts having confronting parallelreaches preceded by confronting converging reaches, means for moving thebelts through the confronting reaches in the same direction, a chamberhaving a discharge opening immediately adjacent the entrance to theconfronting converging reaches of the belts, means for delivering fibersthrough the chamber and its discharge opening into the space between theconfronting reaches of the belts, and means for blowing a heat-edgaseous medium through the confronting reaches of the belts and thefibrous material therebetween, said chamber having an air-perviousmember extending transversely of the chamber adjacent the dischargeopening, means for directing one of said belts over the pervious memberimmediately before entering its confronting reach, and means forapplying suction to the side of the pervious member opposite that overwhich the belt passes.

, 4. A machine for making felt-like fibrous webs, mats, batts or thelike comprising a pair of air-pervious belts having confronting reachesmoving in the same direction, a plurality of pairs of rolls spaced apartin the direction of movement of the confronting reaches, the confrontingreach of one of the belts passing over one roll of each pair, theconfronting reach of the other belt passing over the other roll of eachpair, the spacing between the individual rolls of at least two pairsother than the pair adjacent the entrance of the belts to theirconfronting reaches being substantially the same and being less than thespacing between the rolls of the pair adjacent said entrance to therebyprovide a converging portion followed by a parallel-spaced portionbetween the confronting belt reaches, a chamber having a dischargeopening immediately adjacent the entrance to the confronting convergingreaches of the belts, means for delivering fibers through the chamberand its discharge opening into the space between the confronting reachesof the belts, and means for blowing a heated gaseous medium through theconfronting reaches of the belts and the fibrous material therebetween,said chamber having an air-pervious member extending transversely of thechamber adjacent the discharge opening, means for directing one of saidbelts over the pervious member immediately before entering itsconfronting reach, and means for applying suction to the side of thepervious member opposite that over which the belt passes.

5. A machine for making felt-like fibrous webs, mats, batts, or the likecomprising a pair of airpervious belts having confronting parallelreaches preceded by confronting converging reaches, means for moving thebelts through the confronting reaches in the same direction, a chamberhaving a discharge opening immediately adjacent the entrance to theconfronting converging reaches of the belts, means for delivering fibersthrough the chamber 11 r and its discharge opening into the spacebetween the confronting reaches of the belts, and means for blowing aheated gaseous medium through the confronting reaches of the belts andthe fibrous material therebetween, said chamber having an air-perviousfalse bottom extending transversely of the chamberadjacent the dischargeopening, :means for directing one of said belts over the pervious falsebottom immediately before entering its confronting reach, and means forapplying suction to the side of the pervious false bottom opposite thatover which the belt passes.

dividual rolls of at least two pairs other than the pair adjacent .theentnance of the belts to their confronting reaches being substantiallythe same and being less than the spacing between the rolls of the pairadjacent said entrance to thereby provide a converging portion followedby a parallel-spaced portion between the confronting belt reaches, achamber having a discharge opening immediately adjacent the entrance tothe confronting converging reaches of the belts, means for deliveringfibers through the chamber and its discharge opening into the spacebetween theconfronting reaches of the belts, and means for blowing ,aheated gaseous medium through the confronting reaches of the belts andthe fibrous material therebetween, said chamber having an air-perviousfalse bottom extending transversely of the chamber adjacent thedischarge opening, means for directing one of said belts over thepervious false bottom immediately before entering its confronting reach,:and means for applying suction to the side of the pervious false bottomopposite that over which the belt passes.

References Cited in the file of this patent UNITED STATES PATENTS Re.22,090 Powell May 5, 1942 40,087 Waite Sept. 22, 1863 1,365,878 WeissJan. 18, 1921 1,786,669 Manning Dec. 30, 1930 1,813,750 Mackenzie July7, 1931 2,152,901 Manning Apr. v4, 1939 2,335,757 Hall Nov. 30, 19432,357,392 Francis Sept. 5, 1944 2,383,849 Davies Aug. 28, 1945 2,577,784Lynam Dec. 11, 1951 FOREIGN PATENTS 355,930 Italy Jan. 20, 1938

